1. Field of the Invention
The invention relates generally to the design of packer assemblies and, in particular aspects, relates to packer devices and methods that are useful in open-hole wellbore portions having irregular surfaces.
2. Description of the Related Art
Packers are devices that are selectively set within a wellbore to form a fluid seal. Ordinarily, the packer uses a sealing element formed of Nitrile or another elastomer to form the seal. An isolation packer is used to create a fluid seal barrier between two zones within a wellbore. Conventional packer designs generally fall into one of two categories: compression-type and inflatable-type packers. Compression packers essentially consist of an elastomeric packer element that surrounds a central mandrel. The packer element is compressed axially by a setting sleeve. As the element is axially compressed, it also expands radially outwardly and contacts the inner surface of the surrounding wellbore, casing, liner or other tubing. Inflatable packers also have an elastomeric packer element that surrounds a mandrel. However, the packer element is radially expanded away from the mandrel by injection of a fluid (typically air or hydraulic fluid) into a space between the packer element and the mandrel. As the packer element expands radially, it contacts that inner surface of the surrounding wellbore, casing, liner or other tubing.
A problem exists in forming fluid seal in open-hole (i.e., uncased) sections of borehole. Open-hole wellbore portions present irregular, often rough, surfaces. Conventional packers are sometimes unable to create a complete fluid seal due to the surface irregularities. Both compression and inflation type packer devices tend to expand outwardly in a uniform fashion around the mandrel. It can be difficult to create a complete seal without stressing the sealing element beyond its intended limits.
The present invention addresses the problems of the prior art.